Control device having buttons with multiple-level backlighting

ABSTRACT

A control device may have a plurality of buttons that may be backlit to multiple levels, such as first, second, and third adjacent buttons positioned in order, and first, second, and third LEDs positioned to illuminate a respective button. The control device may be configured to illuminate the first LED to a first LED illumination intensity to illuminate the respective button to a first surface illumination intensity; illuminate the third LED to a second LED illumination intensity to illuminate the respective button to a second surface illumination intensity; and illuminate the second LED to a third LED illumination intensity to illuminate the respective button to the second surface illumination intensity. The third LED illumination intensity may be less than the second LED illumination intensity, which may be less than the first LED illumination intensity, and the second surface illumination intensity may be less than the first surface illumination intensity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/244,556, filed Jan. 10, 2019, which is a continuation of U.S. patentapplication Ser. No. 15/952,869, filed Apr. 13, 2018, now U.S. Pat. No.10,206,260, issued Feb. 12, 2019, which is a continuation of U.S. patentapplication Ser. No. 15/680,516, filed Aug. 18, 2017, now U.S. Pat. No.9,980,335, issued May 22, 2018, which is a continuation of U.S. patentapplication Ser. No. 14/850,315, filed Sep. 10, 2015, now U.S. Pat. No.9,763,302, issued Sep. 12, 2017, which claims the benefit of U.S.Provisional Application No. 62/166,204, filed May 26, 2015, and U.S.Provisional Application No. 62/048,658, filed Sep. 10, 2014, which areincorporated by reference herein as if fully set forth.

BACKGROUND

Home automation systems, which have become increasing popular, may beused by homeowners to integrate and control multiple electrical and/orelectronic devices in their house. For example, a homeowner may connectappliances, lights, blinds, thermostats, cable or satellite boxes,security systems, telecommunication systems, and the like to each othervia a wireless network. The homeowner may control these devices using acontroller, a remote control device (e.g., such as a wall-mountedkeypad), or user interface provided via a phone, a tablet, a computer,and the like directly connected to the network or remotely connected viathe Internet. These devices may communicate with each other and thecontroller to, for example, improve their efficiency, their convenience,and/or their usability.

A control device may include a plurality of buttons where, for example,each button may control a different device and/or control a device to apreset level or intensity. It may be desirable to backlight the buttonsof the control device so that a user may easily see them if the room isdark. Backlighting may also be used to indicate which of the buttons iscurrently set, for example, by setting that button to a higher intensitylevel than the others. However, variables such as ambient lightingconditions, button color, location and configuration of the controldevice, etc. may adversely affect how the backlighting is perceived by auser, for example, by reducing the readability of the buttons, reducingthe contrast between selected and unselected buttons, and/or the like.As such, there exists a need for a backlight solution that providesconsistent backlighting intensities and prevents bleed through of lightbetween buttons regardless of the ambient light in the room, the colorof the buttons, the configuration of the control device and/or the like.

SUMMARY

The present disclosure relates to a load control system for controllingthe amount of power delivered to an electrical load, such as a lightingload, and more particularly, to a keypad having buttons withbacklighting for use in a load control system.

A control device may include one or more buttons and have multiple-levelbacklighting. For example, the control device may include a controlcircuit, a first button, a second button, a third button, a first LED, asecond LED, and a third LED. The first, second, and third LEDs may beconfigured to illuminate at least a portion of a respective one of thefirst, second, and third buttons. The control circuit may beelectrically coupled to the first, second, and third buttons and thefirst, second, and third LEDs. The control circuit may be configured toilluminate the first LED to a first LED illumination intensity toilluminate the first button to approximately a first surfaceillumination intensity, illuminate the third LED to a second LEDillumination intensity to illuminate the third button to approximately asecond surface illumination intensity, and illuminate the second LED toa third LED illumination intensity to illuminate the second button toapproximately the second surface illumination intensity. The second LEDillumination intensity may be less than the first LED illuminationintensity. The third LED illumination intensity may be less than thesecond LED illumination intensity, and the second surface illuminationintensity may be less than the first surface illumination intensity.

The control device may include an ambient light detector. The ambientlight detector may be configured to generate an ambient light detectsignal. The control circuit may be configured to receive the ambientlight detect signal and, based on the ambient light detect signal,determine an ambient light level in the room in which the control deviceis installed. One or more of the first LED illumination intensity, thesecond LED illumination intensity, or the third LED illuminationintensity may be based at least in part on the ambient light level. Thecontrol circuit may be configured to determine illumination caused by atleast one of the first LED, the second LED, or the third LED, anddetermine the ambient light level based on the illumination caused by atleast one of the first LED, the second LED, or the third LED, forexample, to compensate for the illumination of one or more LEDs in theambient light detect signal. The control circuit may be configured todetect a change in the ambient light level, and adjust the first LEDillumination intensity, the second LED illumination intensity, and/orthe third LED illumination intensity based on the change in the ambientlight level.

The first button may include indicia (e.g., text), and the second buttonmay be closer to the indicia than the third button. The first button maybe in a selected state. The first LED illumination intensity may bedetermined based on an active adjustment curve DC_(ACTIVE), and thesecond LED illumination intensity and the third LED illuminationintensity are based on an inactive adjustment curve DC_(INACTIVE).

The control device may include a communication circuit configured totransmit control signals. For example, the control circuit may beelectrically coupled to the communication circuit, and the controlcircuit may be configured to control at least one electrical load inresponse to at least one of the first button, the second button, or thethird button receiving a user input. The control device may beconfigured to be electrically connected to an AC power source.

A control device may comprise a plurality of buttons, a plurality ofLEDs, and a control circuit. Each of the LEDs may be configured toilluminate at least a portion of a respective button of the plurality ofbuttons. The control circuit may be electrically coupled to theplurality of buttons and the plurality of LEDs. The control circuit maybe configured to determine that a button of the plurality of buttons isin a selected state. The control circuit may be configured to illuminatethe LED of the selected button to a first LED illumination intensity toilluminate at least a portion of the selected button to approximately afirst surface illumination intensity based on the button being in theselected state. The control circuit may be configured to illuminate theLEDs of each of the remaining buttons to respective illuminationintensities to illuminate at least a portion of each of the remainingbuttons to approximately a second surface illumination intensity. Thesecond surface illumination intensity may be less than the first surfaceillumination intensity. The respective illumination intensities of theLEDs of each of the remaining buttons may be based on the relativeposition of each of the remaining plurality of buttons to the selectedbutton. For example, the illumination intensity of an LED of a buttonthat is closer to the selected button may be less than the illuminationintensity of an LED of a button that is further from the selectedbutton.

The control device may include an ambient light detector. The ambientlight detector may be configured to generate an ambient light detectsignal. The control circuit may be configured to receive the ambientlight detect signal and, based on the ambient light detect signal,determine an ambient light level in the room in which the control deviceis installed. The first LED illumination intensity and the LEDillumination intensities of the remaining buttons may be based at leastin part on the ambient light level. The control circuit may beconfigured to determine illumination caused by one or more of theplurality of LEDs, and determine the ambient light level based on theillumination caused by the one or more of the plurality of LEDs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example control device (e.g., awall-mounted keypad) for use in a load control system for controllingthe amount of power delivered to one or more electrical loads.

FIG. 2 is a simplified block diagram of an example control device.

FIG. 3 is a simplified flowchart of an example backlighting procedure.

FIG. 4 illustrates example adjustment curves for adjusting duty cyclesof currents conducted through light-emitting diodes illuminating buttonsof a control device in response to a measured ambient light level on alinear scale.

FIG. 5 illustrates example adjustment curves for adjusting duty cyclesof currents conducted through light-emitting diodes illuminating buttonsof a control device in response to a measured ambient light level on alogarithmic scale.

FIG. 6 is a simplified flowchart of another example backlightingprocedure.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of an example control device (e.g., awall-mounted keypad 100) for use in a load control system forcontrolling the amount of power delivered to one or more electricalloads (e.g., lighting loads). The keypad 100 may comprise a faceplate102 and a plurality of buttons 104 (e.g., four buttons). The pluralityof buttons 104 may be received through an opening 106 of the faceplate102. In one or more examples, the faceplate 102 and/or the buttons 104may have a metallic surface. The faceplate 102 may be configured to beattached (e.g., snapped) to an adapter 108, which may be attached (e.g.,using screws) to an enclosure (not shown) that houses the electricalcircuitry of the control device. The keypad 100 may be electricallyconnected to an alternating-current (AC) power source (not shown) forreceiving power.

The keypad 100 may be configured to transmit a digital message to one ormore external load control device via a communication link forcontrolling respective electrical loads. The communication link maycomprise a wired communication link or a wireless communication link,such as a radio-frequency (RF) communication link. Alternatively and/oradditionally, the keypad 100 may comprise an internal load controlcircuit for controlling the power delivered to one or more electricalloads. For example, the keypad 100 may be configured to control AC powerdelivered from the AC power source to one or more electrical loads.Examples of load control systems having remote control devices, such asthe keypad 100, are described in greater detail in commonly-assignedU.S. Pat. No. 6,803,728, issued Oct. 12, 2004, entitled SYSTEM FORCONTROL OF DEVICES, and U.S. Patent Application Publication No.2014/0001977, published Jan. 2, 2014, entitled LOAD CONTROL SYSTEMHAVING INDEPENDENTLY-CONTROLLED UNITS RESPONSIVE TO A BROADCASTCONTROLLER, the entire disclosures of which are hereby incorporated byreference.

The button 104 may comprise indicia, such as text 120, for indicating apreset (e.g., a lighting scene) or command that may be transmitted inresponse to an actuation of the button 104. Alternatively oradditionally, the indicia on the button 104 may comprise an icon orsymbol. A preset may relate to a particular mode of operation of anelectrical load. For example, if the electrical load is a lighting load,the preset may relate to a particular lighting intensity level of thelighting load. For instance, a “morning” preset may set a lighting loadat a medium-high lighting intensity level (e.g., 70% intensity), a “day”preset may set a lighting load at a high lighting intensity level (e.g.,100% intensity, or full on), an “evening” preset may set the lightingload at a medium-low intensity level (e.g., 30% intensity), and a“night” preset may set the lighting load at a low lighting intensitylevel (e.g., 10% intensity). The one or more presets or commands may bepreconfigured and/or adjusted by the user through a commissioning modeof the keypad 100.

The buttons 104 may be backlit to allow the indicia to be read in a widerange of ambient light levels. Each button 104 may be made of atranslucent (e.g., transparent, clear, and/or diffusive) material. Forexample, the buttons 104 may be made of plastic. The buttons 104 may beilluminated by one or more light sources (e.g., LEDs) located behindand/or to the side of each button (e.g., inside of the keypad 100). Inaddition, the buttons 104 may each have a metallic surface.Specifically, each button 104 may have a translucent body (not shown)and an opaque material, e.g., a metallic sheet (not shown), adhered to afront surface of the body. The text 120 may be etched into the metallicsheet of each button 104 (e.g., through a machining process, lasercutting, photo-etching, or other metal-removal process). Theillumination from the LEDs may shine through the translucent body, butnot through the metallic sheet, such that the text 120 of each button(e.g., that is etched away from the metallic sheet) is illuminated.

Alternatively or additionally, the buttons 104 may be coated withanother type of opaque material, such as paint, and the text 120 may beetched into the paint. For example, the body 112 of the button 104 maybe made of a translucent material, such as glass. The opaque material(e.g., such as paint) may be coated onto the rear surface 118 of thebody 110 and the text 118 may be etched into paint on the rear surfaceof the body. Moreover, the faceplate 102 of the keypad 100 may comprisea metallic sheet and text or other indicia etched into the metallicplate and backlit by LEDs located behind the faceplate.

The keypad 100 may operate to backlight the buttons 104, such that thetext 120 of a selected preset (e.g., an “active” preset) is illuminatedto an active surface illumination intensity L_(SUR1), and the text ofeach of the other presets (e.g., “inactive” presets) is illuminated toan inactive surface illumination intensity L_(SUR2). The active surfaceillumination intensity L_(SUR1) may be greater than the inactive surfaceillumination intensity L_(SUR2), such that a user may identify which ofthe presets is selected based upon the intensity of the illumination ofthe text 120.

The ambient light level in the room in which the keypad 100 is installedmay affect a user's ability to read the text 120 on the buttons 104. Forexample, if the contrast between the brightness of the illuminated text120 and the brightness of the adjacent surface of the button 104 is toolow, the illuminated text may appear washed out to the user. Factorssuch as the ambient light, the color of the buttons, the color of thewalls, ceilings, and floors in the room, and the like may contribute. Assuch, the user may not be able to identify which of the presets isselected (e.g., “active”) based on the intensity of the illumination ofthe text 120.

Accordingly, the keypad 100 may comprise an ambient light detectioncircuit, which may be located inside of the keypad and may be configuredto measure the ambient light level in the room in which the keypad 100is installed. For example, the keypad 100 may comprise an opening 130 inthe adapter 108 through which the ambient light detection circuit mayreceive light to make a determination of the ambient light level in theroom. Alternatively or additionally, the keypad 100 may comprise anopening in the faceplate 102 and/or one or more of the buttons 104 forallowing the ambient light detection circuit to receive light. Inaddition, the ambient light detection circuit may be configured toreceive light through the gaps between the buttons 104 and/or throughthe material of the buttons. The ambient light detection circuit mayalso be positioned behind a semi-transparent or dark window and may beconfigured to receive light through the window. The keypad 100 maycomprise a light pipe for directing light from outside of the keypad tothe ambient light detection circuit.

The keypad 100 may be configured to adjust the active and inactivesurface illumination intensities LSUR₁, LSUR₂ in response to themeasured ambient light level. For example, the keypad 100 may beconfigured to increase the active and inactive surface illuminationintensities LSUR₁, LSUR₂ if the ambient light level increases, anddecrease the active and inactive

FIG. 2 is a simplified block diagram of an example control device 200that may be deployed as, for example, the keypad 100 shown in FIG. 1.The control device 200 may comprise a control circuit 210, which mayinclude one or more of a processor (e.g., a microprocessor), amicrocontroller, a programmable logic device (PLD), a field programmablegate array (FPGA), an application specific integrated circuit (ASIC), orany suitable processing device. The control device 200 may comprise oneor more actuators 212 (e.g., mechanical tactile switches), which may beactuated in response to actuations of the buttons 104. The controlcircuit 200 may be coupled to the actuators 212 for receiving userinputs.

The control device 200 may further comprise a communication circuit 214,such as, a wired communication circuit or a wireless communicationcircuit (e.g., an RF transmitter coupled to an antenna for transmittingRF signals). The control circuit 210 may be coupled to the communicationcircuit 214 for transmitting digital messages in response to actuationsof the actuators. Alternatively or additionally, the communicationcircuit 214 may include an RF receiver for receiving RF signals, an RFtransceiver for transmitting and receiving RF signals, and/or aninfrared (IR) transmitter for transmitter IR signals. In addition, thecontrol circuit 210 may be configured to receive a digital messageincluding, for example, a selected preset and/or the status of anelectrical load controlled by an external load control device.

The control device 200 may also include a memory 216 communicativelycoupled to the control circuit 210. The control circuit 210 may beconfigured to use the memory 216 for the storage and/or retrieval of,for example, commands and/or preset information to transmit in responseto actuations of the buttons 104. The memory 216 may be implemented asan external integrated circuit (IC) or as an internal circuit of thecontrol circuit 210. The memory 216 may include one or more componentsof volatile and/or non-volatile memory, in any combination.

The control device 200 may also comprise a power supply 218 forgenerating a direct-current (DC) supply voltage V_(CC) for powering thecontrol circuit 210, the communication circuit 214, the memory 216, andthe other low-voltage circuitry of the control device. The power supply218 may be coupled to an alternating-current (AC) power source or anexternal DC power source via electrical connections 219. Alternativelyor additionally, the control device 200 may comprise an internal powersource (e.g., one or more batteries) in place of or for supplying powerto the power supply 218.

The control device 200 may further comprise a backlighting circuit 220for illuminating indicia on one or more buttons (e.g., the buttons 104of the keypad 100). For example, the backlighting circuit 220 maycomprise four LEDs 222 coupled to respective ports on the controlcircuit 210 via respective resistors 224. The control circuit 210 isconfigured to individually turn each LED 222 on by pulling therespective port low towards circuit common, such that the LED is coupledbetween the supply voltage V_(CC) and circuit common through therespective resistor 224. The control circuit 210 may be configured todim the illumination of each LED 222, e.g., by pulse-width modulatingthe LED current conducted through each LED and adjusting a duty cycleDC_(LED) of the respective pulse-width modulated LED current.

While the control device 200 shown in FIG. 2 has one LED 222 forilluminating each of the buttons 104, each LED illustrated in FIG. 2 maycomprise one or more LEDs coupled in series or parallel. For example,each LED 222 in FIG. 2 may comprise four LEDs coupled in series. Forexample, the LEDs 222 may comprise white LEDs, e.g., part numberLTW-C191DS5-LR, manufactured by LITE-ON. Each of the resistors 224coupled in series with the respective LEDs 222 may have a resistancesized such that the maximum average magnitude of LED current may beapproximately 20 mA, for example.

The control circuit 210 may be configured to backlight the buttons 104,such that the text 120 of a specific button (e.g., a button having textindicating a selected preset, herein referred to as “the selectedbutton”) is illuminated to an active surface illumination intensityL_(SUR1), and the text of each of the other buttons (e.g., thenon-selected or inactive buttons) is illuminated to an inactive surfaceillumination intensity L_(SUR2). The inactive surface illuminationintensity L_(SUR2) may be less than the active surface illuminationintensity L_(SUR1). To illuminate the text of one of the buttons 104 tothe active surface illumination intensity L_(SUR1), the control circuit210 may pulse-width modulate the LED current through the LED 222 behindthe button using a first LED duty cycle DC_(LED1) to cause therespective LED 222 to illuminate to a first LED illumination intensityL_(LED1). To illuminate the text of one of the buttons 104 to theinactive surface illumination intensity LSUR₂, the control circuit 210may pulse-width modulate the LED current through the LED 222 behind thebutton using a second LED duty cycle DC_(LED2) (e.g., approximately 15%)to cause the respective LED 222 to illuminate to a second LEDillumination intensity L_(LED2), which may be less that the first LEDillumination intensity L_(LED1).

The control device 200 may further comprise an ambient light detector230 (e.g., an ambient light detection circuit) for measuring an ambientlight level LAMB in the room in which the control device 200 isinstalled. The ambient light detector 230 may generate an ambient lightdetect signal V_(AMB), which may indicate the ambient light level LAMBand may be received by the control circuit 210. The control circuit 210may receive the ambient light detect signal V_(AMB) and determine theambient light level LAMB accordingly. The ambient light level LAMB mayinclude, for example, illumination from daylight, one or more lightingloads in the room, and/or the like.

The control circuit 210 may be configured to adjust the first and secondLED illumination intensities L_(LED1), L_(LED2) in response to themeasured ambient light level LAMB as determined from the ambient lightdetect signal V_(AMB). For example, the control circuit 210 may beconfigured to adjust the first duty cycle DC_(LED1) of the LED currentthrough the LED 222 behind the button having the active preset inresponse to the measured ambient light level LAMB, and to adjust thesecond duty cycle DC_(LED2) of the LED current through each of the LEDs222 behind the buttons having the inactive presets in response to themeasured ambient light level LAMB. For example, the control circuit 210may be configured to increase the first and second LED illuminationintensities L_(LED1), L_(LED2) to increase the active and inactivesurface illumination intensities L_(SUR1), L_(SUR2) if the ambient lightlevel increases. The control circuit 210 may be configured to decreasethe first and second LED illumination intensities L_(LED1), L_(LED2) todecrease the active and inactive surface illumination intensitiesL_(SUR1), L_(SUR2) if the ambient light level decreases.

The control device 200 may account for reflection of light generated bythe LEDs 222 of the buttons when determining the ambient light levelLAMB. For example, illumination from the LEDs 222 of the buttons mayreflect off the wall, floor, ceiling, control device 200 itself, etc.and alter the measured ambient light level L_(AMB). This may depend onthe particular installation of the control device 200, the color of theceiling, floor, and/or wall of the room, etc. For example, if an openingfor the ambient light detector 230 is provided along the bottom of thefaceplate (e.g., as is the case with opening 130 in FIG. 1), the LED 222behind the bottom button may cause inaccuracies in the ambient lightlevel LAMB calculated by the ambient light detector 230. In someinstances, the illumination caused by the LEDs 222 may cause runaway inthe ambient light level LAMB (e.g., the ambient light detector 230 maycalculate the ambient light to include illumination from the LED 222,the control circuit 210 may increase the LED intensity to compensate forthe ambient light, which in turn may increase the measured ambient lightlevel L_(AMB)).

Accordingly, the control device 200 may calculate the part of theambient light level LAMB caused by the LEDs 222 and remove the lightcaused by the LEDs 222 from the ambient light level LAMB. For example,the control device 200 may calculate the part of the ambient light levelLAMB caused by the LEDs 222 using the intensity level of the LEDs (e.g.,which is known to the control circuit 210) and/or the degree of bleedand/or reflection of the respective LEDs 222 (e.g., which may bepreconfigured in the control circuit 210 or determined during acommissioning step). Alternatively or additionally, the control device200 may comprise an isolation element, such as light blocking foam,between the ambient light detector 230 and the LEDs 222 to preventand/or reduce inaccuracies in the ambient light level LAMB caused by theillumination of the LEDs 222.

Illumination from the LED 222 behind the selected button may affect thesurface illumination intensity of the adjacent buttons such that, forexample, the surface illumination intensity of the adjacent buttons isnot equal to the second surface illumination intensity L_(SUR2). Forexample, the illumination from the LED 222 behind the selected buttonmay shine directly on and/or be reflected or refracted onto the rearsurfaces of the bodies of the adjacent buttons and cause the surfaceillumination intensity of the adjacent buttons to increase (e.g., and inturn, not be equal to the inactive surface illumination intensityL_(SUR2)). Accordingly, the control device 200 may be configured toadjust the illumination intensity of an LED 222 of a button based on itsrelative proximity to the selected button, for example, to cause all ofthe buttons other than the selected button to be illuminated to theinactive illumination intensity LSUR₂. For example, the control circuit210 may be configured to decrease the intensities of the LEDs 222 of thebuttons next to the selected button below the inactive LED illuminationintensity L_(LED2), such that the resulting illumination intensity ofthe text on the buttons is equal to the inactive surface illuminationintensity L_(SUR2).

As described, the control device 200 may be configured to adjust theillumination intensity of an LED 222 of a button based on its relativeproximity to the selected button, for example, to ensure that thebuttons other than the selected button are illuminated to the inactiveillumination intensity L_(SUR2). The control device 200 may utilizecorrection factors to determine the intensities of the LEDs 222 of thebuttons other than the selected button. The correction factors may varybased on the intensity of the LEDs 222 of the selected and unselectedbuttons. For example, the ratio between the intensities of the selectedand unselected buttons may be greater at lower light levels (e.g., up toa 15× difference) than at higher light levels (e.g., as low as a 3×difference), for example, because the human focal system may have lessability to differentiate between light at low intensity levels. And theratios may be configured based on external factors, such as the color ofthe walls, ceiling, floors, keypad, etc.

The control device 200 may use a constant percentage as a correctionfactor to determine the intensities of the LEDs 222 of the buttons basedon their relative position with respect to the selected button. In oneor more embodiments, the control device 200 may perform a closed-loopcommission operation (e.g., when the control device 200 is firstinstalled) to determine one or more correction factors to used whendetermining the intensities of the LEDs 222 of the buttons based ontheir relative position to the selected button. Then during normaloperation, the control circuit 210 may operate in an open-loop mode.When performing the closed-loop operation, the control device 200 maystore each of the variables used when determining the correction factors(e.g., which button is the selected button, the various loads being on,the ambient light level LAMB, etc.). Alternatively or additionally,commissioning may be performed via the use of a smart phone. Forexample, a picture of each combination of variables (e.g., with eachbutton being the selected button) may be taken by a smart phone, sent tothe cloud, and the control device 200 may receive one or more correctionfactors accordingly. In one or more examples, the control device 200 mayuse the ambient light level LAMB to determine and/or refine theintensities of the LEDs 222 of the buttons next to the selected button.

The specific location of the indicia on the buttons may affect how andwhich buttons are affected by the illumination from the LEDs 222 behindthe selected button. For example, the text on the buttons 104 may belocated towards the topside of the buttons, such as is shown in FIG. 1.In such instances, the illumination from the LED 222 behind the selectedbutton may have a greater effect on the surface illumination of thebutton right above the selected button than the button below theselected button. For example, the LED 222 behind the selected button maycause a first predetermined amount of change Δ_(LED1) (e.g.,approximately 9%) on the button below the selected button and a secondpredetermined amount of change Δ_(LED2) (e.g., approximately 15%) on thebutton above the selected button.

Accordingly, the control circuit 210 may be configured to adjust theillumination intensity of an LED 222 of a non-selected button based onits relative proximity to the indicia of the selected button. Forexample, the control circuit 210 may be configured to control the LED222 of the button closest to the text of the selected button to anillumination intensity that is less than the illumination intensity ofthe LED 222 of the button that is further from the text of the selectedbutton (e.g., to compensate for any reflection or fraction of light fromthe LED 222 of the selected button). For example, assuming the text islocated towards the topside of the buttons, the control circuit 210 maybe configured to control the LED 222 of the button below the selectedbutton to a third LED illumination intensity L_(LED3) and to control theLED 22 of the button above the selected button to a fourth LEDillumination intensity L_(LED4) that is less than the third LEDillumination intensity L_(LED3). For example, the control circuit 210may be configured to control the illumination of each of the LEDs to thethird and fourth LED illumination intensities L_(LED3), L_(LED4) bycontrolling the LED current through the respective LED using respectivethird and fourth LED duty cycles DC_(LED3), DC_(LED4) (e.g.,approximately 5% and 1%, respectively). If the text on the buttons 104is located towards the center of the buttons, the control circuit 210may be configured to control the LEDs of the buttons below and above theselected button to the same LED illumination intensity.

The example values of the duty cycles used to control the illuminationof the LEDs 222 to the first, second, third, and fourth LED illuminationintensities L_(LED1)-L_(LED4) provided herein are examples values, whichfor example, may be used when the bodies 110 of the buttons 104 are madefrom a translucent plastic. The values of the LED illuminationintensities may vary depending upon the material of the buttons 104, thesize, shape, and location of the indicia on the buttons 104, the numberand size of LEDs 222, and/or the like.

The control device 200 may compensate for the degradation of the LEDsover their lifecycle. For example, using the ambient light detector 230,the control device 200 may determine that the light output from the LEDsof each button does not correspond to their set LED illuminationintensity L_(LED). The control device 200 may determine the actual lightoutput of the LEDs based on the set LED illumination intensity L_(LED)and the ambient light level LAMB measured by the ambient light detector230. For example, the control device 200 may be placed in acommissioning mode (e.g., when the control device 200 is firstinstalled), where the control device 200 determines the ambient lightlevel L_(AMB) with the LEDs off, then turns the LEDs behind each buttonon and measures the difference in ambient light level LAMB to determinea baseline value for the LED illumination intensity L_(LED) of the LEDsof each button. Using that baseline value, the control device 200 maydetermine whether the actual light output from the LEDs of each buttoncorresponds to the set LED illumination intensity L_(LED). As the actuallight output of the LEDs degrades over time, the control device 200 mayincrease the LED illumination intensity L_(LED) to compensate for thedegradation of the LEDs. The control device 200 may perform this testperiodically (e.g., once every predetermined amount of time, such asevery six months), when commissioned by a user, and/or the like.

FIG. 3 is a simplified flowchart of an example backlighting procedure300 that may be executed periodically by the control circuit 210 forbacklighting the buttons 104. At 310, the control circuit 210 may set aselected-button number N_(SEL) to be equal to the presently selectedbutton (e.g., due to the presently selected preset or scene). Forexample, the number N_(SEL) may be one for the top button, two for thesecond button, three for the third button, and four for the bottombutton of the keypad 100 shown in FIG. 1. In other words, if the Eveningbutton is the selected button, the control circuit 210 will set thenumber N_(SEL) to three at 310. During the backlighting procedure 300,the control circuit 210 may step through the LEDs 222 behind each of thebuttons 104 and determine the correct LED illumination intensity foreach of the buttons. The control circuit 210 may use a variable n forstepping through the LEDs during the backlighting procedure 300. At 312,the control circuit 210 may initialize the variable n to one.

If the variable n is equal to the selected-button number N_(SEL) at 314(e.g., the present button is the selected button), the control circuit210 may control the nth LED to the first LED illumination intensityL_(LED1) at 316. If the variable n is equal to the selected-buttonnumber N_(SEL) plus one at 318 (e.g., the button below the selectedbutton), the control circuit 210 control the nth LED to the third LEDillumination intensity L_(LED3) at 320. If the variable n is equal tothe selected-button number N_(SEL) minus one at 322 (e.g., the buttonabove the selected button), the control circuit 210 control the nth LEDto the fourth LED illumination intensity L_(LED4) at 324. The fourth LEDillumination intensity L_(LED4) may be less than the third LEDillumination intensity L_(LED3), for example, if the indicia on thebuttons is located near the topside of the buttons as shown in FIG. 1.If the variable n is not equal to the selected-button number N_(SEL)minus one at 322, the control circuit 210 may control the nth LED to thesecond LED illumination intensity L_(LED2) at 326. In one or moreexamples, if the variable n is not equal to the selected-button numberN_(SEL) minus one at 322, the control circuit 210 may control the nthLED to an LED illumination intensity L_(LED) that is dependent upon thebutton's relative location with respect to the selected-button at 326.

After setting the LED illumination intensity at 316, 320, 324, and 326,the control circuit 210 may determine if the variable n is equal to amaximum number N_(MAX) (e.g., the number of buttons 104 on the keypad100) at 328. If the variable n is not equal to the maximum numberN_(MAX) at 328, the control circuit 210 increments the variable n by oneat 330, and the procedure 300 loops around the set the LED illuminationintensity for the next LED. If the variable n is equal to the maximumnumber N_(MAX) at 328, the procedure 300 exits.

As previously mentioned, the ambient light level in the room in whichthe keypad is installed may affect a user's ability to read the text onthe buttons. Accordingly, the control circuit 210 may be configured toadjust the first, second, third, and fourth LED illumination intensitiesL_(LED1), L_(LED2), L_(LED3), L_(LED4) by adjusting the respective dutycycle DC_(LED1), DC_(LED2), DC_(LED3), DC_(LED4) in response to theambient light level LAMB measured by the ambient light detector circuit230. The control circuit 210 may adjust the selected (e.g., or active)button according to one adjustment curve and the unselected (e.g., orinactive) buttons according to a different adjustment curve. Forexample, the control circuit 210 may be configured to adjust the firstduty cycle DC_(LED1) of the LED current through the LED behind thebutton having the active preset in response to the measured ambientlight level LAMB according an active LED adjustment curve DC_(ACTIVE),and to adjust the second duty cycle DC_(LED2) of the LED current througheach of the LEDs behind the buttons having the inactive presets inresponse to the measured ambient light level LAMB according an inactiveLED adjustment curve DC_(INACTIVE). The third and fourth LED duty cyclesDC_(LED3), DC_(LED4) may be calculated using the inactive duty cyclecurve DC_(INACTIVE) and/or the second LED duty cycle DC_(LED2). Theactive LED adjustment curve DC_(ACTIVE) and the inactive LED adjustmentcurve DC_(INACTIVE) may be stored in the memory 216.

FIGS. 4 and 5 illustrate example active and inactive adjustment curvesDC_(ACTIVE), DC_(INACTIVE) for adjusting the duty cycle DC_(LED) of theLED current through each of the LEDs in response to the measured ambientlight level LAMB. FIG. 4 shows an example active and inactive adjustmentcurves DC_(ACTIVE) and DC_(INACTIVE) on a linear scale, while FIG. 5shows an example active and inactive adjustment curves DC_(ACTIVE) andDC_(INACTIVE) on a logarithmic scale. For example, if the measuredambient light level LAMB is approximately 500 Lux, the first duty cycleDC_(LED1) of the LED current through the LED behind the control buttonhaving the active preset may be controlled to approximately 66%, whilethe second duty cycle DC_(LED2) of the LED current through each of theLEDs behind the control buttons having the inactive presets may becontrolled to approximately 17%.

The human eye has a more difficult time discerning contrast in lowambient light levels than in high ambient light levels. Thus, the firstduty cycle DC_(LED1) of the active adjustment curve DC_(ACTIVE) may be,for example, over ten times greater than the second duty cycle DC_(LED2)of the inactive adjustment curve DC_(INACTIVE) near a minimum ambientlight level L_(AMB-MIN) (e.g., approximately 0 Lux), for example, asshown in FIGS. 4 and 5. Near a maximum ambient light level LAMB-MAX(e.g., approximately 1000 Lux), the first duty cycle DC_(LED1) of theactive adjustment curve DC_(ACTIVE) may be, for example, approximatelythree times greater than the second duty cycle DC_(LED2) of the inactiveadjustment curve DC_(INACTIVE).

The active and inactive adjustment curves DC_(ACTIVE) and DC_(INACTIVE)are non-linearly related (e.g., not proportional), for example, asillustrated in FIGS. 4 and 5. The difference between the active andinactive adjustment curves DC_(ACTIVE) and DC_(INACTIVE) may benon-linear as the ambient light level ranges from the minimum ambientlight level L_(AMB-MIN) to the maximum ambient light level LAMB-MAX. Thevalues of the active and inactive adjustment curves DC_(ACTIVE) andDC_(INACTIVE) may be chosen so that the button 104 having the text ofthe active preset may be visually distinguished (e.g., visuallybrighter) than the buttons 104 having the text of the inactive presetsacross a range of typical ambient light levels (e.g., between theminimum ambient light level LAMB-MIN and the maximum ambient light levelL_(AMB-MAX)). The values of the active and inactive adjustment curvesDC_(ACTIVE) and DC_(INACTIVE) may also be chosen so that the text 120 onboth the button 104 having the text of the active preset and the buttons104 having the text of the inactive presets may be read across a rangeof typical ambient light levels (e.g., between the minimum ambient lightlevel L_(AMB-MIN) and the maximum ambient light level L_(AMB-MAX)).

FIG. 6 is a simplified flowchart of an example backlighting procedure400 that may be executed periodically by a control circuit (e.g., thecontrol circuit 210) for backlighting a plurality of buttons of acontrol device (e.g., the buttons 104 of the keypad 100). The controlcircuit 210 may sample the ambient light detect signal V_(AMB) at 410.The control circuit 210 may determine the measured ambient light levelLAMB using the magnitude of the ambient light detect signal V_(AMB) at412. The control circuit 210 may determine the first LED duty cycleDC_(LED1) from the active adjustment curve DC_(ACTIVE) (e.g., as shownin FIG. 4 or 5) using the measured ambient light level LAMB at 414. Thecontrol circuit may determine the second LED duty cycle DC_(LED2) fromthe inactive adjustment curve DC_(ACTIVE) using the measured ambientlight level LAMB at 416. At 418, the control circuit 210 may set aselected-button number N_(SEL) to be equal to the presently selectedbutton (e.g., the button having text indicating the active or selectedpreset or scene). During the backlighting procedure 400, the controlcircuit 210 may step through the LEDs 222 behind each of the buttons 104and determine the correct LED illumination intensity for each of thebuttons. The control circuit 210 may use a variable n for steppingthrough the LEDs during the backlighting procedure 400. At 420, thecontrol circuit 210 may initialize the variable n to one.

If the variable n is equal to the selected-button number N_(SEL) at 422(e.g., the present button is the selected button), the control circuit210 may control the LED current conducted through the LED behind theselected button using the first LED duty cycle DC_(LED1) at 424. If thevariable n is equal to the selected-button number N_(SEL) plus one at426 (e.g., the button below the selected button), the control circuit210 may calculate the third LED duty cycle DC_(LED3) at 428. Forexample, the control circuit 210 may calculate the third LED duty cycleDC_(LED3) based at least in part on the first predetermined amount ofchange Δ_(LED1) caused by the LED behind the selected button on thebutton below the selected button, e.g.,DC_(LED3)=DC_(LED2)−(DC_(LED1)−DC_(LED2))·Δ_(LED1).At 430, the control circuit 210 may pulse-width modulate the LED currentconducted through the LED behind the button below the selected buttonusing the third LED duty cycle DC_(LED3).

If the variable n is equal to the selected-button number N_(SEL) minusone at 432 (e.g., the button above the selected button), the controlcircuit 210 may calculate the fourth LED duty cycle DC_(LED4) at 434.For example, the control circuit 210 may calculate the fourth LED dutycycle DC_(LED3) based at least in part on the second predeterminedamount of change Δ_(LED2) caused by the LED behind the selected buttonon the button above the selected button, e.g.,DC_(LED4)=DC_(LED2)(DC_(LED1)−DC_(LED2))·Δ_(LED2).At 436, the control circuit 210 may pulse-width modulate the LED currentconducted through the LED behind the button above the selected buttonusing the fourth LED duty cycle DC_(LED4). If the variable n is notequal to the selected-button number N_(SEL) minus one at 432, thecontrol circuit 210 may pulse-width modulate the LED current conductedthrough the nth LED using the second LED duty cycle DC_(LED2) at 438. Inone or more examples, if the variable n is not equal to theselected-button number N_(SEL) minus one at 432, the control circuit 210may control the nth LED to an LED illumination intensity L_(LED) that isdependent upon the button's relative location with respect to theselected-button at 438.

After setting the LED illumination intensity at 424, 430, 436, and 438,the control circuit 210 may determine if the variable n is equal to amaximum number N_(MAX) (e.g., the number of buttons 104 on the keypad100) at 440. If the variable n is not equal to the maximum numberN_(MAX) at 440, the control circuit 210 may increment the variable n byone at 442, before the procedure 400 loops around the set the LEDillumination intensity for the next LED. If the variable n is equal tothe maximum number N_(MAX) at 440, the procedure 400 may simply exit.

The invention claimed is:
 1. A control device comprising: a backlightingcircuit including a first light source, a second light source, and athird light source; a first button having a first indicia configured tobe illuminated by the first light source; a second button having asecond indicia configured to be illuminated by the second light source;a third button having a third indicia configured to be illuminated bythe third light source, the first button located between the second andthird buttons; and a control circuit responsive to actuations of thefirst, second, and third buttons, and electrically coupled to the first,second, and third light sources of the backlighting circuit, the controlcircuit configured to: control the first light source to emit light at afirst source illumination intensity to illuminate the first indicia onthe first button; control the second light source to emit light at asecond source illumination intensity to illuminate the second indicia onthe second button; and control the third light source to emit light at athird source illumination intensity to illuminate the third indicia onthe third button; wherein the control circuit is configured to set bothof the second and third source illumination intensities of the secondand third buttons, respectively, using one or more correction factors sothat the second and third source illumination intensities are both lessthan the first source illumination intensity and the first indicia onthe first button is illuminated to a brighter intensity than therespective indicia on the second and third buttons, the control circuitfurther configured to set the second source illumination intensity to beless than the third source illumination intensity so that the second andthird buttons are illuminated to the same intensity.
 2. The controldevice of claim 1, wherein respective correction factors of the secondand third buttons are based on the relative positions of the second andthird buttons with respect to the first button.
 3. The control device ofclaim 2, wherein the control circuit is configured to vary at least oneof the correction factors based on the first, second, and third sourceillumination intensities.
 4. The control device of claim 2, wherein eachof the correction factors is a constant percentage.
 5. The controldevice of claim 2, wherein the first indicia on the first button islocated closer to the second button than the third button.
 6. Thecontrol device of claim 1, further comprising: a communication circuitconfigured to receive digital messages; wherein the control circuit isconfigured to receive the correction factors via the communicationcircuit.
 7. The control device of claim 1, further comprising: acommunication circuit configured to transmit digital messages; whereinthe control circuit is configured to transmit, via the communicationcircuit, a digital message for controlling an electrical load inresponse to an actuation of the first button, the second button, or thethird button.
 8. The control device of claim 1, wherein the controlcircuit is configured to perform a closed-loop commission operation todetermine the respective correction factors of the second and thirdbuttons.
 9. The control device of claim 1, wherein the control device iselectrically connected to an AC power source; and wherein the controlcircuit is configured to control an amount of power delivered from theAC power source to an electrical load in response to an actuation of thefirst button, the second button, or the third button.
 10. The controldevice of claim 1, further comprising: an ambient light detectorconfigured to generate an ambient light detect signal; wherein thecontrol circuit is configured to receive the ambient light detect signaland to determine an ambient light level in a room in which the controldevice is installed based on the ambient light detect signal, and thecontrol circuit is configured to adjust the first, second, and thirdsource illumination intensities based on the ambient light level. 11.The control device of claim 1, further comprising: first, second, andthird tactile switches electrically coupled to the control circuit;wherein the first tactile switch is configured to be actuated inresponse to an actuation of the first button, the second tactile switchis configured to be actuated in response to an actuation of the secondbutton, and the third tactile switch is configured to be actuated inresponse to an actuation of the third button.
 12. A method ofbacklighting buttons of a control device, the control device comprisingfirst, second, and third buttons, and first, second, and third lightsources positioned to illuminate a respective one of the first, second,and third buttons, the method comprising: controlling the first lightsource to emit light at a first source illumination intensity toilluminate first indicia on the first button; controlling the secondlight source to emit light at a second source illumination intensity toilluminate second indicia on the second button; controlling the thirdlight source to emit light at a third source illumination intensity toilluminate third indicia on the third button; setting both of the secondand third source illumination intensities of the second and thirdbuttons, respectively, using one or more correction factors so that thesecond and third source illumination intensities are both less than thefirst source illumination intensity and the first indicia on the firstbutton is illuminated to a brighter intensity than the respectiveindicia on the second and third buttons; and setting the second sourceillumination intensity to be less than the third source illuminationintensity so that the second and third buttons are illuminated to thesame intensity.
 13. The method of claim 12, further comprising: settingrespective correction factors of the second and third buttons are basedon the relative positions of the second and third buttons with respectto the first button.
 14. The method of claim 13, wherein setting therespective correction factors further comprises varying at least one ofthe correction factors based on the first, second, or third sourceillumination intensities.
 15. The method of claim 13, wherein settingthe respective correction factors further comprises setting each of thecorrection factors to be a constant percentage.
 16. The method of claim13, wherein setting the respective correction factors further comprisesperforming a closed-loop commission operation to determine therespective correction factors of the second and third buttons.
 17. Themethod of claim 12, further comprising: controlling an amount of powerdelivered from an AC power source to an electrical load in response toan actuation of the first button, the second button, or the thirdbutton.
 18. The method of claim 12, further comprising: transmitting adigital message for controlling an electrical load in response to anactuation of the first button, the second button, or the third button.19. The method of claim 12, further comprising: receiving a digitalmessage including the correction factors.
 20. The method of claim 12,further comprising: controlling the first light source to emit light atthe first source illumination intensity to illuminate the first indiciaon the first button to approximately a first surface illuminationintensity; controlling the second light source to emit light at thesecond source illumination intensity to illuminate the second indicia onthe second button to approximately a second surface illuminationintensity; and controlling the third light source to emit light at thethird source illumination intensity to illuminate the third indicia onthe third button to approximately the second surface illuminationintensity.